RED ALDER LEAF LITTER AND STREAMWATER QUALITY IN WESTERN OREGON

WATER RESOURCES BULLETINVOL. 22, NO. 4 AMERICAN WATER RESOURCES ASSOCIATION AUGUST 1986

RED ALDER LEAF LITTER AND STREAMWATERQUALITY IN WESTERN OREGON'

R. Lynn Taylor and Paul W. Adams2

ABSTRACT: Streamside red alder (Alnus rubra Bong.) stands are com-mon in western Oregon, and they have been suspected of causingwater quality problems in domestic supplies during autumn leaf fall.Studies in the Seaside municipal watershed showed potential waterquality effects (particularly increased color) from alder leaves, butstream sampling during 1981-82 revealed no chronic problems. Thefew observed short-term increases in water color occurred near theonset of storm flows, which suggested a flushing of organic matterstorage sites. An extended period of unusually low flows and high leaffall are probably necessary to produce significant water quality prob-lems in this stream system. Laboratory leaching of alder leaves infiltered stream water indicated a fairly constant release of coloredorganic matter over time, and running water leached this matter moreefficiently than still water. Water color increased linearly with in-creasing leaf mass added to still water, and for a given leaf mass thereappeared to be a limit to the amount of colored matter that couldbe removed in the first 48 hours of leaching. Other laboratory testsshowed that ultraviolet absorbance (254 mm) may provide a reasonableestimate of dissolved organic carbon concentrations in systemsdominated by alder leaf inputs.(KEY TERMS: riparian vegetation; forests; municipal watersheds;water quality; water color; red alder (Alnus rubra Bong.).

INTRODUCTION

Leaves from deciduous vegetation are an important andnatural source of organic matter to many forest streams(Cummins, 1974; Vannote, et al., 1980). Aquatic systemscan, however, become temporarily overloaded with naturalinputs of organic matter that reduce water quality, especiallyfor domestic use. For example, the input of leaves fromdeciduous trees can cause undesirable color, taste, and odorproblems during autumn low flow periods (Allen, 1960; Cor-bett and Heilman, 1975; Slack and Feltz, 1968). Such waterquality changes can also indicate problems for water treat-ment and public health. The efficiency of chlorine as a dis.infectant can be reduced in water containing dissolved organicmatter (LeChevallier, et at., 1981), and chlorination may in-crease undesirable taste and odor through the formation ofhalogenated organics, especially trthalomethanes (THM's)(Rook, 1976; Stevens, et a!., 1976; Symons, et a!., 1975). It

has been suggested that THM's are potentially carcinogenic,although a link between cancer in humans and the ingestionof these compounds in drinking water has not been clearlyestablished (Carlo and Mettlin, 1980; Maugh, 1981; Tuthilland Moore, 1980).

Past logging in western Oregon has resulted in the replace-ment of conifer stands, with red alder stands in the riparianzone of many forest streams. Problems with color, taste, andodor in local water supplies have been observed where thiscondition exists, especially during low flows (State WaterResources Board, 1973). Beyond some general observations,however, there have been no detailed studies of domesticwater quality problems associated with hardwood leaf litterin Oregon. The objective of this research was to provide apreliminary evaluation of some of these problems, focusingon a representative municipal watershed where water treat-ment is limited to chlorination. Specifically, field workwas planned to describe leaf litter inputs and accompanyingstreamwater quality before, during, and after peak autumnleaf fall. Laboratory studies were also designed to clarify therelationships between such variables as leaf quantity, contacttime, and water flow. Water quality evaluations focused onwater color, which was expected to provide a relatively simplebut useful index of overall water quality and organic mattercontent.

STUDY AREA

Leaf litter and streamwater sampling were conducted on theSeaside municipal watershed (Figure 1), located approximately10 km southeast of Seaside, Oregon, on the South Fork ofthe Necanicum River (Lat. 45°53'3', Long. 123°49'55",T.5N, R.9W, Clatsop County, Oregon). The city's diversionis a few kilometers upstream of the confluence of the SouthFork and main Necanicum. At the diversion, the South Forkis a fifth.order stream as determined by the crenulationmethod (Linsley, et at., 1975). Total watershed area above

No. 84203 of the Water Resources Bulletin. Discussions are open until April 1, 1987.2Respectjvely Former Graduate Student Assistant and Associate Professor, Forest Engineering Department, Oregon State University, Corvallis,

Oregon 97331.

629 WATER RESOURCES BULLETIN

Taylor and Adams

the city diversion is 20.2 km2, with three major subbasins(west, middle, and east tributaries for identification purposes)representing 54, 30, and 16 percent of the total area, respec-tively. Mid-October flows at the diversion in 1981 were about1.0 m3/s, while flows at the lower portions of the threetributaries were about 0.4, 0.3 and 0.1 m3/s.

Figure 1. Seaside Municipal Watershed, South ForkNecanicum River, Oregon, with Locations of Water

and Leaf Litter Sample Points.

Mean live stream width and depth at a 1.0 m3/s flowwere estimated at 2.6 in and 6.1 cm, based on measurementsweighted by lengths of the various channels. Channel gradientsrange from about 0.25 percent at the diversion to about 2.5percent for the lower portions of the three tributaries, togreater than 3 percent in the upper reaches. Channel sideslopes generally range from 10-25 percent, with a few greaterthan 40 percent. Streams in the watershed roughly follow apool-riffle-pool sequence, with pools, riffles, runs, cascadesand backwaters representing approximately 35, 35, 20, 7 and3 percent of the stream length, respectively. The bottommaterial is coarse throughout the watershed, primarily com-prised of cobbles and large gravels. There is a small amountof exposed bedrock and very little large organic debris. Upperstream banks are generally uniform and appear stable andwell-vegetated. Major soils on the Seaside watershed aredeep (> 1 m), well-drained silt-loams with an organic matter

content of less than 12 percent (based on soil maps from theUSDA Soil Conservation Service).

Riparian zones in the watershed are dominated by rela-tively uniform red alder (Alnus rubra Bong.) stands, especiallyin the lower portions. These stands developed after har-vesting of previously existing streamside conifer stands andrange from 20-27 years old. Average stem density is about740 trees/ha, mean basal area from 23 to 34 m2/ha, averagediameter at breast height about 23 cm, and average heightbetween 18 to 24 m. Tree canopy cover over streams isquite uniform throughout the watershed, averaging 94 per-cent. Heavy shading results in fairly limited and low-lyingunderstory vegetation.

Field Studies

METHODS

A network of 23 litter collectors (0.25 m2, with 10 cmwooden sides and screen bottoms) was established at 16 loca-tions throughout the watershed (Figure 1) to quantify streamchannel leaf inputs during autumn 1981. Twelve collectorswere placed on iron rods anchored in streams, and the othereleven on upper banks. Leaves were normally collectedweekly and returned to the laboratory, where negligibleamounts of non-alder material were removed, and the remain-ing samples were dried at 50°C for 48 hours and weighed.Water sampling sites were generally at the same locations asthose for leaf sampling and were chosen to follow the waterquality: 1) just above the city diversion, 2) in upstream areaswith potential influence upon downstream water quality, and3) in in-channel and off.channel pools where leaf accumulationand slow-moving or still water occurred together. Pools weresampled where there was also a nearby sampling point formoving water.

Water quality samples and stream temperature measure-ments were taken at the same time as leaf sampling duringautumn 1981. Water sampling was also continued on a monthlybasis at six locations from January through March 1982. Twograb samples, one for general water quality and one for dis-solved oxygen (DO), were taken at each site. The DO sampleswere taken with 300 ml DO bottles and were fixed in the fieldusing Hach dry chemical powder pillows for the azide modifi-cation of the Winkler method (Hach Chemical Co., 1978). Allsamples were covered and placed on ice for transportationback to the laboratory, where they were then refrigeratedat 5°C. The DO titrations were conducted with 0.25 normalphenylarsine oxide (PAO) titrant, usually within eight hoursof sampling. Water quality analyses (true color, conductivity,pH, and nitrate-nitrogen) were usually conducted within 48hours, and followed the standard procedures (American PublicHealth Association, 1980). True color analyses were donewithout filtration if sample turbidity was less than 1 nephelo-metric turbidity unit (NTU). Samples with turbidities greaterthan 1 NTU were filtered with Whatman GF/C glass micro-fibre filters (effective pore size, 0.7 um).


Red Alder Leaf Litter and Streamwater Quality in Western Oregon

Laboratory Studies

Leaching experiments were conducted with dried alderleaves and stream water, under controlled conditions. Leaveswere obtained in early November 1981 by pruning branchesfrom alder trees on forest land near Corvallis, Oregon. Toinhibit decomposition during storage and facilitate weighing,the leaves were dried at 50°C for 48 hours and refrigeratedat 50C in polyethylene bags. Streamwater for the leachingswas collected in March and August 1972, from the SouthFork Necanicum river near the Seaside diversion. The waterwas kept refrigerated and filtered as needed with WhatmanGF/F filters. All still-water leachings were conducted in thedark at 10°C, which was within the temperature range (6.7-18.8°C) found in the South Fork Necanicum in autumn 1981.Leaching of soluble substances from leaves has been shown tobe independent of temperatures in this range (Petersen andCummins, 1974; Barnes, et a!., 1978).

Color generation over time was evaluated with a constantleaf mass and water volume (2.2 g/l) for nine time periods:2, 6, 12, 24, 48, 72, 96, 336, and 648 hours. The first sevenleaching times were expected to show color generation pri-marily due to physical leaching, while the latter were likelyto include effects of microorganisms remaining after fIltra-tion. Five replicate treatment jars were prepared for eachleaching time. The jars were swirled at least once a day toensure complete mixing, and more vigorous stirring was usedto aerate the longer term leachings. Color generation overtime in moving water was observed using three replicaterecirculating chambers (0.2 m/s flow rate), with leaves andwater prepared as above. The leaf mass to water volumeratio was also 2.2 g/l, but larger amounts were used (22 g/10l).After adding the leaves, 50 ml samples were removed foranalysis (and replaced with equal volumes of filtered stream-water) at 2, 6, 12, 24, and 48 hours. Streamwater replace-ment after sampling was expected to cause negligible colordilution in the 10 1 volumes.

The effects of leaf loading on the quality of still stream-water were examined with five replicates of each of the fol-lowing mass/volume ratios, after 48 hours of leaching: 0.25g/l, 0.50 gIl, 1.00 g/l, 2.22 gIl, 5.60 g/l. These amounts wereconsidered to represent a range that would encompass naturalloadings. The 48-hour time interval was again expected toprimarily show the effects of physical leaching. Water sam-ples from each replicate treatment from the three experimentswere filtered with Whatman GF/F filters and analyzed fortrue color, pH, and conductivity. Except for the runningwater experiment, leaves were removed following leaching,dried at 50°C for 48 hours, and reweighed to determineweight loss.

Another experiment was conducted to define the relation-ship between dissolved organic carbon (DOC) in alder leafleachates and light absorbance in the visible (color) and ultra-violet (UV) wavelength ranges. A highly colored leachatewas prepared using 6.66 g/l loading for 48 hours at 10°C.A dilution series was then prepared from filtered (WhatmanCF/F) leachate and analyzed for DOC using wet oxidation

and sealed ampules (Oceanographic International Co., 1978).A spectral absorbance analysis was made on the dilution serieswith a double beam spectrophotometer to determine peakabsorbance. No distinct absorption peaks were found over the200 to 800 nm range, so absorbance measures were made at455 nm (platinum.cobalt color) and 254 nm, the latter ofwhich is used for analyzing a wide variety of organic sub-stances. Because of the sensitivity of UV absorbance at 254nm, a second and more dilute leachate series was preparedfor these measurements.

Field Studies

Average alder leaf fall in riparian zones on the Seasidewatershed in 1981 ranged from about 12 g/m2/week inSeptember to a peak of over 80 g/m2/week in late October(Figure 2). Average cumulative leaf fall between Septemberand December was 322 g/m2, which closely agrees with otherred alder leaf fall data in western Oregon (Zavitkovski andNewton, 1981). Data from individual samplers (not shown)indicated that riparian zone leaf fall was fairly uniformthroughout the watershed.

Water color near the city diversion during autumn 1981ranged from 10 to 30 Pt-Co units and averaged 18±6 Pt-Counits (Figure 2). This is higher than the mean streamwatercolor (9±4 Pt-Co units) observed during winter of 1982.The autumn water color data are based on weekly sampling,and the color could have been even higher between samplingdates. An observed color level of 45 Pt-Co units for a tapwater sample collected in Seaside on October 27 (a day whenstream sampling was not conducted) supports this possibility.

Streamwater near the city diversion showed only a slighttrend of higher color levels with increasing leaf fall, andstreamflow seemed to be a confounding influence (Figure 2).


RESULTS

— Stream FlowLeaf Fall

—.—•. Water Color

OaOc

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0

-j.I'--.-

.J

20

C.,

E15

0-jU.

104'U

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0SEPT 1 OCT 1 NOV 1 DEC 1

Figure 2. Streamflow and Water Color Near the City ofSeaside Diversion and Average Watershed Riparian Zone

Leaf Fall, South Fork Necanicum River, Oregon.

Taylor and Adams

For example, high and low color levels showed some tendencyto occur on the rising and falling limbs of the hydrograph,respectively. Isolated pools within the stream channel showedsome high color levels (Figure 3), whereas color in pools inpartial or direct contact with the flowing stream closely re-sembled the nearby flowing water (data not shown). Stream-water sampling throughout the watershed revealed no specificsource area for observed color at the diversion. The easttributary tended to be the most colored (22±9 Pt-Co units)in autumn 1981, especially during low flows, but it also con-tributed least to the flow of the South Fork Necanicum. Themiddle tributary tended to be the least colored (14±6 Pt-Counits) and carried about 3 times the flow of the east tribu-tary.

Figure 3. Water Color and Dissolved Oxygen in an Isolated Poolon East Tributary of South Fork Necanicum River, Oregon.

Stream dissolved oxygen (DO) near the city diversion re-mained near saturation (10-12 mg/l) during autumn 1981,and the accompanying water temperatures were relativelylow (7-13°C). Isolated poois showed some very low DOlevels, and over time DO fluctuated considerably in thesepoois (Figure 3). Water color in isolated poois appeared tobe inversely related to the DO level. Stream pH at the citydiversion remained within 0.4 pH units above or below neutralduring autumn 1981. During the first three weeks in Septem-4jer the pH was slightly basic, followed by generally slightlyacidic levels during the rest of autumn. Lowest pH levelson the watershed were observed in the isolated pools, but eventhese were only slightly acidic (pH 6.1). Electrical conducti-vity throughout the watershed generally remained under 50umhos/cm. The highest conductivity levels occurred duringearly autumn low flows and in isolated pools, where a valueof 64 umhos/cm was observed. Stream nitrate-nitrogen con-centrations were generally highest during the early autumnflows (0.25-1.00 mg/l). However, nitrate levels dropped andremained consistently low as soon as flows increased ( 0.25mg/I). Only selected stations were monitored after mid-October, and these continued to show low nitrate-nitrogenlevels through the remaining sampling periods.

Laboratory Studies

Under laboratory conditions, alder leaf leaching in stillwater showed a strong linear relationship between Pt-Co colorand duration of leaching (Figure 4). After a relatively rapidcolor increase during the first two hours, color developed at afairly constant rate of about 2 units per hour. Microbial acti-vity eventually becomes significant, as indicated by thedevelopment of cloudy samples at 72 and 96 hours. Leafweight losses, conductivity, and pH also showed distinct pat-terns with duration of leaching (Table 1). Most of the totalleaf weight change observed after 4 weeks of leaching (—30.7percent), occurred during the first 48 hours (—22.0 percent).The greatest rate of change occurred during the fIrst 6 hours(—2.6 percent/hr), with the rate of change decreasing to avery low level after 48 hours (—0.05 percent/hr). Conducti-vity also changed most rapidly during the first 6 hours ofleaching (+4.2 umhos/cm/hr), after which changes were rela-tively small (+0.3 umhos/cm/hr between 6 and 96 hours).Values of pH clearly decreased during the first few days ofleaching (from 6.8 to 5.8 after 72 hours), but then movedback toward the original level, probably due to microbialactivity.

Figure 4. Relationship Between Water Color and Leaching Timeof Red Alder Leaves in Still Water (2.2 g dry leaves/i water;

data clusters represent 5 replicate treatments).

Running water was more efficient than still water ingenerating color from alder leaves, but this difference wasevident only for leaching times greater than 2 hours (Figure 5).The greatest difference in the rates of color generation occurredbetween 2 and 6 hours, after which the rates were similar.The net difference after 48 hours was that running waterproduced a color level about one-and-one-half times that ofstill water. Changes in pH and conductivity of running water


— Water Color- — DIssolved 02a

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LEACHING TIME600

(hours)

Red Alder Leaf Litter and Streaniwater Quality in Western Oregon

showed little difference from the stifi-water leaching. Weightloss from alder leaves in running water was not measured, butother studies have shown that 5 to 30 percent of the originalleaf weight is lost in the first 24 hours (Kaushik and Hynes,1971; Peterson and Cummins, 1974; Short and Ward, 1980).The weight loss in our experiment was probably in the upperend of this range since still-water leaching caused a weightloss of about 17 percent in 24 hours.

TABLE 1. Leaf Weight Changes, and Water Conductivity, pHand Color After Leaching of Red Alder Leaves for Varying

Times in Still Water (2.2 g dry leaves/i water;values are means of 5 replicate treatments).

LeachingTime(hrs)

Leaf WeightChange

(percent)Conductivity(umhos/cm) pH

Color(Pt-Co units)

0 0.0 41 6.8 02 —5.2 53 6.6 iS6 —10.3 66 6.4 22

12 —13.9 72 6.3 3424 —16.6 78 6.2 5848 —22.0 82 6.0 9072 —22.5 83 5.8 13396 —23.7 89 5.9 198

336 —26.4 100 6.5 655648 —30.7 97 6.5 1310

Figure 5. Comparison of Color Generated from Red Alder LeavesLeached in Still and Running Water (2.2 g dry leaves/i water;

data points are means of 3-5 replicate treatments).

Results of the 48-hour mass loading series showed a strongpositive relationship between the quantity of leaves per unitvolume of water and the degree of color development (Fig-ure 6). Strong relationships with leaf mass were also foundwith conductivity (positive) and pH (negative) (Table 2). Thepercent decrease in leaf weight after 48 hours was essentiallythe same regardless of the quantity of leaves leached (Table 2).

a(I)

ECIt)It)

0-j0C.)

LEAF MASS/WATER VOL. (g/l)

Figure 6. Relationship Between Water Color and Mass of RedAlder Leaves Leached in Still Water for 48 Hours

(data clusters represent 5 replicate treatments).

TABLE 2. Leaf Weight Changes, and Water Conductivity,pH, and Color After Leaching Varying Amounts of Red

Alder Leaves for 48 Hours in Still Water (valuesare means of 5 replicate treatments).

Dry Leaf Massto Water Volume

(g/l)

Leaf WeightChange

(percent)Conductivity(umhos/cm) pH

Color(Pt-Co units)

0.00 0.0 41 6.7 00.25 —24.2 49 6.6 190.50 —23.0 54 6.5 291.00 —24.8 65 6.3 552.22 —24.0 88 5.9 945.56 —25.3 170 5.3 225


V 39X + 8.0

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250

200

150

100

50

00 1 2 3 4 5

— Still Water— — — Running Water

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150

100

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012 24 36 48

LEACHING TIME (hours)

Red alder leaf leachate showed a strong linear relationshipbetween DOC and visible light absorbance at 455 nm (Pt-Cocolor) and also between DOC and ultra-violet (UV) absorbanceat 254 nm (Figures 7 and 8). However, for samples with lessthan 30 units of Pt-Co color, the ratios of color/DOC werequite variable. The ratios of UV absorbance/DOC, in con-trast, were relatively constant throughout the range of mea-surement.

DISCUSSION AND CONCLUSIONS

Streamwater color at the city of Seaside diversion duringthe September, 1981 low-flow period (about 20 units) wasslightly higher than the maximum drinking water standard of15 units set by the U.S. Public Health Service (Public HealthService, 1962). This is a relatively low color level, however,

Taylor and Adams

and probably would not generate many complaints or aes-thetic concerns. Notable color was also occasionally observedin the stream and in Seaside tap water later in the season,typically on the rising limb of a storm hydrograph. Thissuggests that, as flows rise, storage sites for leaf materialand dissolved organics are accessed and enough material isquickly added to increase water color. This would probablyoccur only a few times in early autumn when low flows alloworganic matter to accumulate between storms that flush ma-terial through the system.

Of the several possible sites of organic matter accumulationthat could have contributed to the observed color increasesduring increasing stream flows, no single source stands out.Isolated pools were present but were relatively infrequent andsmall. Soils in the watershed are not high in organic matter,which otherwise can notably contribute to water color viasubsurface flow (Christman and Ghassemi, 1966). However,organic matter leaching and transfer via subsurface flow withinthe stream channel and riparian zone could be particularlyimportant, even though our sampling could not distinguish thisspecific source.

Other water quality parameters measured on the Seasidewatershed in 1981-82 were consistent with the observation thatalder leaf fall did not have a substantial chronic impact onwater color in autumn, 1981. For example, DO concentra-tions remained near saturation ( 8 mg/l) at all flowingstream stations sampled. Conductivity remained low ( 55

umhos/cm) in flowing water and showed little difference be-tween fall and winter values. The flowing stream pH levelswere somewhat higher during the September low-flow periodthan at higher flows but varied no more than 0.7 pH units.

The laboratory results demonstrate the potential for alderleaves to cause rapid and substantial color changes in stream-water. Appreciable increases in water color occurred afterjust 2 hours of contact time, and color continued to increasefor up to 4 weeks of leaching. A relatively constant rate ofcolor generation was observed over this period, which suggeststhat the process of removing colored material from leaves re-mains fairly uniform. This probably represents primarily aphysical breakdown and leaching, although after a few daysmicrobial decay may also become significant. Running wateris generally more efficient than still water in removing coloredcompounds from alder leaves, very likely because material isquickly carried away from leaf surfaces. This efficient removalis apparently most important during intermediate stages ofleaching (2-6 hours).

Water color after 48 hours of leaching appears to bedirectly related to the mass of alder leaves present per unitvolume of water. In addition, the percent of the original dryweight of leaves that was lost remained fairly constant regard-less of the mass loading level, indicating that there is a limitto the amount of material that can be physically leached froma given leaf mass over a short period. Although the laboratoryresults may not directly match those in the field, it is likelythat the ratio of leaf mass to water volume is a primary deter-minant of water color in streams where alder leaves are themajor source of organic matter. Where leaf inputs are uniform,two notable controlling factors would be flow and contacttime. Watershed characteristics such as area and morphologywould obviously be important in influencing streamfiow andvelocity and the subsequent dilution and contact time ofwater with leaf material.

Pt-Co color and UV absorbance measurements may be use-ful in estimating simply and inexpensively DOC concentrationsin aquatic systems dominated by red alder leaves. The sensiti-vity and consistency of UV absorbance for evaluating DOC are


Y 2.5x-2.7

2 0.99

100 200 300COLOR (455 nm abs.)

600aC)

400

0

200

00

Figure 7. Relationship Between Dissolved Organic Carbon (DOC)and Water Color in Leachates from Red Alder Leaves.

150

!io:

0

Figure 8. Relationship Between Dissolved OrganicCarbon (DOC) and Ultraviolet (UV) Absorbance

in Leachates from Red Alder Leaves.

Y 54.7X+1.9

R 2 0.99

0 1.0 2.0 3.0UV ABSORBANCE (254 nm)

Red Alder Leaf Litter and Streamwater Quality in Western Oregon

particularly attractive. Of course, both techniques must beverified using water samples collected in the field.

The field and laboratory observations, when combined withestimates of leaf inputs and streamfiows for the entire SouthFork Necanicun-i watershed, suggest that this stream system isnormally too large and fast-flowing to show chronic waterquality problems due to autumn leaf inputs. Water color inthis stream system can certainly reach noticeable levels butsuch conditions should be sporadic and short-lived. Chroniccolor and other water quality problems from alder leaf litter,however, could occur in other watersheds in the Pacific North-west. Stream systems with lower flows and similar leaf inputs,streams with many pools or low velocity, and small reservoirswith significant leaf inputs are some situations that couldproduce such problems. Each individual watershed and watersupply system must be carefully examined to accuratelyevaluate existing and potential water quality problems thatmay be attributable to red alder leaf litter.

ACKNOWLEDGMENTS

This research was supported in part by a grant from the U.S. De-partment of the Interior, Office of Water Research and Technology,through the Water Resources Rese'rch Institute, Oregon State Univer-sity, Corvallis, Oregon.

LITERATURE CITED

Allen, J. E., 1960. Taste and Odor Problems in New Reservoirs inWooded Areas. J. Am. Water Works Assoc. 52:1017-1032.

American Public Health Association, 1980. Standard Methods for theExamination of Water and Wastewater, 15th Edition. AmericanPublic Health Association, New York, New York.

Barnes, J. R., R. Ovink, and K. W. Cummins, 1978. Leaf LitterProcessing in Gull Lake, Michigan, USA. Verh. Internat. Verein.Limnol. 20:475-479.

Carlo, G. L. and C. J. Mettlin, 1980. Cancer Incidence and Trihalo-methane Concentrations in a Public Drinking Water System. Am.J. of Pub. Health 70(5):523-525.

Christman, R. F. and M. Ghassemi, 1966. Chemical Nature of OrganicColor in Water. J. Am. Water Works Assoc. 58 (Pt. 2):723-741.

Corbett, E. S. and J. M. Heilman, 1975. Effects of Management Prac-tices on Water Quality and Quantity: The Newark, New Jersey,Municipal Watersheds. In: Municipal Watershed Management Sym-posium Proceedings, USDA Forest Service Gen. Tech. Rep. NE-13:47-5 7.

Cummins, K. W., 1974. Structure and Function of Stream Ecosystems.BioScience 24(11):631-641.

Hach Chemical Co., 1978. Direct Reading Engineers Laboratory(DR-EL/2), Methods Manual, 3rd Edition.

Kaushik, N. K. and H. B. N. Hynes, 1971. The Fate of Dead Leavesthat Fall Into Streams. Arch. Hydrobiol. 68(4):465-515.

LeChevallier, M. W., T. M. Evans, and R. J. Seidler, 1981. Effect ofTurbidity on Chlorination Efficiency and Bacterial Persistence inDrinking Water. Applied and Environ. Microbiol. 42(1): 159-167.

Linsley, R. K., M. A. Kihler, and L. H. Paulhus, 1975. Hydrology forEngineers. McGraw-Hill, Inc., 2nd Edition.

Maugh, T. H., 1981. New Study Links Chlorination and Cancer.Science 211:694.

Oceanographic International Co., 1978. Total Carbon System Opera-ting Procedures. Oceanograliic International Co., College Station,Texas.

Petersen, R. C. and K. W. Cummins, 1974. Leaf Processing in a Wood-land Stream. Freshwater Biol. 4:343-368.

Public Health Service, 1962. Drinking Water Standards, 1962. Pub.Health Serv. Publ. 956. U.S. Govt. Printing Office, Washington,D.C.

Rook, J. J., 1976. Haloforms in Drinking Water. J. Am. Water WorksAssoc. 68(Pt. 1):168-172.

Short, R. A. and J. V. Ward, 1980. Leaf Litter Processing in a Regu-lated Rocky Mountain Stream. Can. J. Fish. Aquat. Sci. 37(1):123-127.

Slack, K. V. and H. R. Feltz, 1968. Tree Leaf Control on Low FlowWater Quality in a Small Virginia Streani. Environ. Sci. and Tech.2(2) 126-13 1.

State Water Resources Board, 1973. Municipal Watershed Sourcebook,Outline for Oregon. Oregon State Water Resources Board, Salem,Oregon.

Stevens, A. A., C. J. Slocum, D. R. Seeger, and G. G. Robeck, 1976.Chlorination of Organics in Drinking Water. J. Am. Water WorksAssoc. 68(Pt. 2):615-620.

Symons, J. M., T. A. Bella, J. K. Carswell, J. DeMarco, K. L. Kropp,G. G. Robeck, D. R. Seeger, C. J. Slocum, B. L. Smith, and A. A.Stevens, 1975. National Organics Reconnaissance Survey for Halo-genated Organics. J. Am. Water Works Assoc. 67:634-647.

Tuthill, R. W. and G. S. Moore, 1980. Drinking Water Chlorination:A Practice Unrelated to Cancer Mortality. J. Am. Water WorksAss. 72(Pt. 2):570-573.

Vanriote, R. L., G. W. Minshall, K. W. Cummins, J. R. Sedell, and C. E.Cushing, 1980. The River Continuum Concept. Canad. J. Fishand Aquat. Sci. 37:130-136.

Zavitkovski, J. and M. Newton, 1971. Litterfall and Litter Accumula-tion in Red Alder Stands in Western Oregon. Plant and Soil 35:257-268.


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RED ALDER LEAF LITTER AND STREAMWATER QUALITY IN WESTERN OREGON